This study attempts to determine to establish a simple, but precise and accurate method for simultaneously determining insulin secretion, action, and glucose effectiveness in humans. The study involves computerized infusions of insulin and glucose, while developing mathematical models to assess the above. To date, we successfully completed the majority of the experiments and have demonstrated that glucose disposal in the presence of increased insulin concentrations is greater than that in the presence of basal insulin concentrations. We are now in the process of completing the saline control experiments. Preliminary analysis of various models suggests that SG* (glucose effectiveness) differs depending upon different insulin concentrations. 2 people withdrew from the study: 1 after screening, 1 after completing study #1.